Transplants comprising a plant growing in a discrete and separate mass of growing medium, known as a plug, or more simply as plant seedlings have traditionally been planted by hand or by means of a semi-automatic machine which generally performs one or more of the following functions:
(i) A rotating set of cups receive a manually selected and placed plant. PA1 (ii) The plant cup mechanically opens and drops the plant via free fall to the ground height. PA1 (iii) A mechanical pushing mechanism pushes the transplant out of the rear of the soil opening shoe. PA1 (iv) A variety of machines variously drop plants into a belt with finger wires to assist in guiding the plant tops in an attempt to hold the plant vertical. PA1 (v) Other mechanical transplanting mechanisms remove every plug regardless of whether or not a plug contains a living plant which causes gaps in the plant spacing in the field. PA1 (a) A continuous movement of plugs from the container tray to the ground with no provision for gapping up that is a separate zone able to move plants at different speeds to another zone with the ability to change one zone speed from stationary to very high speed and transfer the seedling to another zone. PA1 (b) No provision for separate areas of plant storage or provision for sorting plugs not containing plants from plugs with plants.
In all of the manual and automatic transplanters described there is:
It is accepted that 10-15% of tray cells in a nursery tray of seedlings will not contain a live seedling suitable for transplanting into the field. This will result in a market gardener or the like having to have additional workers to hand plant seedlings in the missing gaps. A more difficult problem may result if the machine not only leaves gaps but also plants seedlings too close together which require workers to manually dig out and replant such seedlings. In the case of celery, for example, 45,000 seedlings are planted per acre and 15% missing live seedlings in the trays amounts to 6750 gaps or misses per acre that have to be manually planted. In Australian Patent Application No. 46909/93 there is disclosed an arrangement which will allow seedlings to be transplanted from trays into a field position with their spacing substantially uniform, however, this arrangement, while working satisfactorily is relatively complicated and therefore expensive to produce. Field planting machinery of this general type also desirably requires a number of other capabilities including the ability for adjacent rows of planted seedlings to be closely adjacent one another and in some cases down to eight inch row centres and that it be capable of simple connection to and operation from conventional tractors commonly used by nursery men and market gardeners.
The current practice of mechanically pushing a plant out of the soil opening shoe is reliant on the plants dropping vertically over a long distance and arriving at the correct time to coincide with the plant pushing mechanism and then pushing only to the shoe edge. This results in very variable planting in terms of the precise height of the plug relevant to the soil surface and the angle of the plant with some plants with broad leaf foliage having leaves being buried. A particular case in point is the necessity with lettuce plants to have the top of the plug level with the soil surface.
If the plug top is above the soil surface, evaporation and wicking occurs causing the plant plug to very rapidly dry out. If the plug top is below the soil surface, the soil then being in contact with or surrounding the stems and leaf area at the base of the plant will cause crown rot to set in with the loss of the plants.
Furthermore, planting often takes place in windy conditions resulting in plants blowing over in the wind before they are positioned correctly and enveloped with soil.
The objective therefore of the present invention is to provide improved machinery of the aforementioned type that is capable of transplanting seedlings from trays directly into ground planting positions, preferably with uniform ground spacing, and preferably constructed in a relatively uncomplicated manner. A further objective of the present invention is to provide improved devices for use in transplanting machinery of the aforementioned type.